Fetal central nervous system (CNS) abnormalities affect approximately 6000 neonates per year in the United States. The majority of these cases have enlarged ventricles(ventriculomegaly) on sonography. However, prenatal. sonography in the evaluation. of ventriculomegaly has limited specificity, is at times technically difficult, and can miss associated findings. Magnetic resonance imaging (MRI) now has the potential to provide an adjunct to the ultrasound exam of the fetus and to impact diagnosis and management of fetal CNS abnormalities in cases where ultrasound is nondiagnostic. We hypothesize that the improved anatomic detail provided by ultrafast MRI ii' fetuses with the sonographic diagnosis of ventriculomegly will significantly impact diagnosis and management of the obstetric patient and/or the newborn infant. The specific aims are to evaluate fetuses with sonographically diagnosed ventriculomegaly with ultrafast MRI and: 1) optimize imaging protocols for evaluation of the fetal CNS; 2) assess the accuracy of prenatal MR; and 3) evaluate if additional information 'provided by MRI directly affects maternal, and/or neonatal care. The research design is as follows: patients in the second and third trimesters of pregnancy will be recruited after diagnosis by ultrasound of enlarged ventricles. Films will be read by specialists in obstetric ultrasound arid neuroradiology The plan for patient management will be recorded before and after the MR examination. The gold standard', lot anomalies will be postnatal physical examination as well. as findings at postnatal. imaging, surgery, pathology, and autopsy. In a pilot project 1.1 patients have undergone MR examinations for the indication of a suspected fetal CNS abnormality In all patients, MRI allowed for visualization of the sonographically identified region of anomaly. In six cases the MR exam added additional information not available with ultrasound; in each case this information altered the sonographic diagnosis. The health relatedness of the project is that the enhanced diagnostic capability of fetal MRI could significantly impact crucial decisions, such as 'the need for prenatal diagnosis of abnormal chromosomes, the tin mg of the delivery and preparation for emergent postnatal care of the infant. Thus the results of this study could significantly decrease morbidity of fetuses with ventriculomegaly.